Question

Read this list of substances: Spirit, camphor, petrol, ghee, coconut oil, naphthalene balls, and ammonium chloride (navsagar).

1. Which ones freeze in winter?
2. Which liquid have you seen change into a vapour?
3. Which solids directly change into the gaseous state?

What do we learn from this?

Answer 1

1. Ghee and coconut oil may freeze or become solid in winter.
2. Spirit and petrol change into vapour easily. Water also changes into water vapour when heated.
3. Camphor, naphthalene balls and ammonium chloride (navsagar) can directly change from solid to gas. This process is called sublimation.

We learn that substances can change from one state to another. A solid can change into a liquid or gas, and a liquid can change into a gas. These changes can occur due to heating or cooling.